Battery Drain Insights Yes, for a while. After a macOS update the Mac rebuilds its search index and other records in the background, and that work uses battery. It usually takes some hours and ends by itself. If the battery is still draining fast after two or three days, the update is no longer the reason, and something else is working.
Why does a Mac use more battery after an update?
The main reason is Spotlight, the search built into macOS. Apple says its indexing happens when you first set up a device, after you install a software update or upgrade, and as data changes (Apple, About Spotlight indexing and search results on Apple devices). After an update the Mac goes through your files again so that search keeps working.
Other parts of the system and some apps redo work of their own after an update. All of it runs in the background, with no window, which is why the Mac feels busy while you are doing nothing.
How long does it last?
Apple gives no number in hours. It says indexing can take some time, depending on how much there is to index. A Mac with few files is done soon. A Mac with many years of documents, mail and photos needs longer, and the work pauses whenever the Mac sleeps.
What Mac owners commonly report on Apple’s support forum is a few hours up to a day or two after a large update. That range is a report, not a promise from Apple.
How do I tell indexing from a real problem?
Three checks, quickest first.
- Press Command and Space to open Spotlight. While indexing is running, Spotlight shows a progress indicator at the top of its window. Apple describes this check on the page above.
- Open Activity Monitor and click Energy. Choose View, All Processes. During indexing, the programs near the top have names that begin with
mdsormdworker. Those are Spotlight. - Look again the next day. If the same names are still at the top after two or three days of normal use, or if the top of the list is something else, the update is not the cause.
What should I do while it is indexing?
- Leave the Mac plugged in and awake for a night. Indexing stops when the Mac sleeps, so a Mac that is only used on battery in short sessions takes days to finish.
- Do not restart it again and again. That does not speed it up.
- Do not rebuild the Spotlight index unless search itself is broken. Rebuilding starts the work from the beginning.
Then use the Mac as usual. There is nothing to repair.
What if it does not stop?
Then treat it as you would on any other day. An update is a common moment for other things to change:
- An app has not caught up with the new macOS and is working harder than before. Look for an update to the app.
- A setting is different from what you chose. Open System Settings, Battery, and check Low Power Mode and, under Options, Wake for network access.
- A background program was added by something you installed around the same time. The article on background items shows where to look.
- The battery was already worn and the update made you look. Check Battery Health on the same Battery page.
The guide Why is my MacBook battery draining so fast? goes through each of these with the steps.
Where Battery Drain Insights fits
Battery Drain Insights shows which programs did the work while you were on battery, so the question “is it still the update?” has an answer you can read. After a few days it also knows what is normal for your Mac, and says when a time on battery cost more than usual.
One limit applies here. Some of the system’s own programs run under the system’s account, and macOS does not let an app from the App Store see how hard they work. The app lists them and marks them as not measured. For those, Activity Monitor is the place to look.